Cathodoluminescence, Raman and scanning electron microscopy with energy dispersion system mapping to unravel the mineralogy and texture of an altered Ca-Al-rich inclusion in Renazzo CR2 carbonaceous chondrite

An altered fluffy type A Ca-Al-rich inclusion in the CR2 Renazzo carbonaceous chondrite was examined by combined Raman, scanning electron microscopy with energy dispersion system (SEM-EDS) and cathodoluminescence (CL) mapping. Blue CL at 450 nm and orange emission at 600 nm were related to anorthite and calcite, respectively. Raman spectra were highly fluorescent, and only the stronger peaks of anorthite, clinopyroxene and calcite were observed. Raman-induced fluorescence emission was measured using the 632-nm Raman laser source, up to 850 nm, and used to chart the mineral phases. A fluorescence structured peak at 690 nm, split in three subpeaks at 678, 689 and 693 nm, was found; it is likely related to the fluorescence emission of Cr3+ from a fassaitic pyroxene in anorthite. Secondary pyroxene in the Wark–Lovering rim does not show the peak at 690 nm; the different fluorescence emission from the secondary rim and the pyroxene patches within anorthite could be a marker to spot the primary pyroxene. From combined imaging, the events in the altered chondrite could be sequenced. Starting from a pristine assemblage of spinel and melilite, with little fassaite, several alteration episodes occurred. Alteration in secondary anorthite, which could be mapped by the blue CL emission at 450 nm, was followed by alkalization, with rims of sodalite and nepheline, and subsequent formation of secondary clinopyroxene, encircling the inclusion. Widespread calcite alteration, present also in the matrix between chondrules, was the last recorded event

A survey of high-z galaxies: serra simulations

We introduce SERRA, a suite of zoom-in high-resolution (1.2 ×104 M⊙, ≃ 25 pc at z = 7.7) cosmological simulations including non-equilibrium chemistry and on-the-fly radiative transfer. The outputs are post-processed to derive galaxy ultraviolet (UV) + far-infrared (FIR) continuum and emission line properties. Results are compared with available multiwavelength data to constrain the physical properties [e.g. star formation rates (SFRs), stellar/gas/dust mass, metallicity] of high-redshift 6 ≲ z ≲ 15 galaxies. This flagship paper focuses on the z = 7.7 sub-sample, including 202 galaxies with stellar mass 107 M⊙ ≲ M⊙ ≲ 5 ×1010 M⊙, and specific star formation rate ranging from sSFR ∼100 Gyr-1 in young, low-mass galaxies to ∼10 Gyr-1 for older, massive ones. At this redshift, SERRA galaxies are typically bursty, i.e. they are located abo v e the Schmidt-Kennicutt relation by a factor κs = 3.03+4.9-1.8, consistent with recent findings for [O III ] and [C II ] emitters at high z. They also show relatively large InfraRed eXcess (IRX = LFIR/LUV) values as a result of their compact/clumpy morphology effectively blocking the stellar UV luminosity. Note that this conclusion might be affected by insufficient spatial resolution at the molecular cloud level. We confirm that early galaxies lie on the standard [C II ] -SFR relation; their observed L[OIII]/L [CII] ≃ 1-10 ratios can be reproduced by a part of the SERRA galaxies without the need of a top-heavy initial mass function and/or anomalous C/O abundances. [O I] line intensities are similar to local ones, making ALMA high-z detections challenging but feasible ( ∼6 h for an SFR of 50 M⊙yr-1)

A survey of high-z galaxies: SERRA simulations

Galaxie

The ALMA REBELS Survey : Average [CII] 158μm Sizes of Star-forming Galaxies from z~7 to z~4

We present the average [C II] 158 μm emission line sizes of UV-bright star-forming galaxies at z ~ 7. Our results are derived from a stacking analysis of [C II] 158 μm emission lines and dust continua observed by the Atacama Large Millimeter/submillimeter Array (ALMA), taking advantage of the large program Reionization Era Bright Emission Line Survey. We find that the average [C II] emission at z ~ 7 has an effective radius re of 2.2 ± 0.2 kpc. It is ≥2× larger than the dust continuum and the rest-frame UV emission, in agreement with recently reported measurements for z ≤ 6 galaxies. Additionally, we compared the average [C II] size with 4 < z < 6 galaxies observed by the ALMA Large Program to INvestigate [C II] at Early times (ALPINE). By analyzing [C II] sizes of 4 < z < 6 galaxies in two redshift bins, we find an average [C II] size of re = 2.2 ± 0.2 kpc and re = 2.5 ± 0.2 kpc for z ~ 5.5 and z ~ 4.5 galaxies, respectively. These measurements show that star-forming galaxies, on average, show no evolution in the size of the [C II] 158 μm emitting regions at redshift between z ~ 7 and z ~ 4. This finding suggests that the star-forming galaxies could be morphologically dominated by gas over a wide redshift range

The ALMA REBELS Survey: Average [C ii] 158 μm Sizes of Star-forming Galaxies from z ∼ 7 to z ∼ 4

We present the average [C ii] 158 μm emission line sizes of UV-bright star-forming galaxies at z ∼ 7. Our results are derived from a stacking analysis of [C ii] 158 μm emission lines and dust continua observed by the Atacama Large Millimeter/submillimeter Array (ALMA), taking advantage of the large program Reionization Era Bright Emission Line Survey. We find that the average [C ii] emission at z ∼ 7 has an effective radius re of 2.2 ± 0.2 kpc. It is ≳2× larger than the dust continuum and the rest-frame UV emission, in agreement with recently reported measurements for z ≲ 6 galaxies. Additionally, we compared the average [C ii] size with 4 < z < 6 galaxies observed by the ALMA Large Program to INvestigate [C ii] at Early times (ALPINE). By analyzing [C ii] sizes of 4 < z < 6 galaxies in two redshift bins, we find an average [C ii] size of re = 2.2 ± 0.2 kpc and re = 2.5 ± 0.2 kpc for z ∼ 5.5 and z ∼ 4.5 galaxies, respectively. These measurements show that star-forming galaxies, on average, show no evolution in the size of the [C ii] 158 μm emitting regions at redshift between z ∼ 7 and z ∼ 4. This finding suggests that the star-forming galaxies could be morphologically dominated by gas over a wide redshift range

Media e Territorio. L'impresa la cultura l'arte del viaggio in Italia nella stampa turistica

Gli ultimi prodotti della tecnologia di navigazione satellitare hanno provocato una vera rivoluzione nella pianificazione e gestione 'in diretta' di percorsi turistico culturali. Una rivoluzione ad altissimo valore aggiunto ludico-informazionale. Ogni angolo di strada, roggia, tabernacolo, ciglione,pieve, crocicchio, fossato, balza, vallata, picco, parco, sentiero, tratturo, giacimento, cava, ecc., è oggi implementabile di informazione statistica, storico-artistica, socio-economica, tassonomica sia mediante la consultazione diretta del data base dedicato, sia mediante l’utilizzo di link a siti, forum e blog specialistici. Il collegamento satellitare ed il conseguente puntamento 'dal cielo' dell’oggetto desiderato ne consente una ‘conquista polimorfa’: all'avvicinamento 'fisico', a piedi o con mezzi, si combina quello 'virtuale' mediante una progressiva zoommata satellitare ed un sapiente accumularsi di net-nozioni. Modalità iperrealistica e vagamente retro-postmodern di mediatizzazione del territorio nella sua forma di ‘sistema di prodotti consumer’, un «sapere sempre (di più) dove si è…», una specie di sestante mercantile impropriamente dedicato a tracciare e omologare segmenti di prodotto/patrimonio ambiental-culturale, piuttosto che a creare ricchezza direzionando lo scambio tra ‘diversità’ sapienti e industriose. Mediatizzazione del ‘territorio’ che va affrontata partendo dai ‘fondamentali’ socio-culturali ed economico-industriali per capirne il ruolo strategico nell’affermarsi di un processo mondiale di globalizzazione dei mercati. Dei tanti approcci, quello testimoniato dalla piccola ma significativa tessera descritta in questo saggio, ci sembra essere uno dei più interessanti e dei più frequentati da studiosi e scienziati di diverse e multidisciplinari competenze: storici dello scambio culturale’, socio-politologi delle migrazioni, economisti , semiologi e antropologi ecc.: mi riferisco all’approccio comunicazionale che legge, nella profonda e larga storia del viaggio, le storie trasversali che ne hanno stratificato le esperienze, le strategie collettive e e le ‘metamorfosi economiche’, ricavandone ipotesi e teorie che consentono di descrivere i processi complessi di valorizzazione che hanno interessato le regioni storiche ed i territori della progressiva e aggressiva antropizzazione del pianeta. L'approccio che valorizza lo svilupparsi in Italia negli ultimi quarant'anni della stampa turistica periodica apre un percorso di ricerca trasversale di estremo interesse per gli studi sullo sviluppo delle città e dei territori e della nascita delle scienze del paesaggio

Data for: Displacement-dependent microstructural and petrophysical properties of deformation bands and gouges in poorly lithified sandstone deformed at shallow burial depth (Crotone Basin, Italy)

Supplementary material concerning the adopted parameters for the grain size analysis, and detailed permeability sampling sites along the investigated fault zone.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Fingerprints and energy budget of the earthquake cycle in shallow sediments

Earthquake cycle consists of alternating transient coseismic slip and long-lasting interseismic periods, covering a wide range of slip rates. Unveiling the deformational signature of earthquake cycles in major seismogenic fault systems is an essential component of seismic hazard evaluation. Here, we present a study combining field and microstructural data acquired from an extensional fault zone with ∼100 m displacement, developed in poorly lithified siliciclastic sediments of the Crotone Basin, South Italy. The maximum burial depth of faulted sediments did not exceed 500 m. Within the fault core a dense network of mutually cross-cutting dark gouges and deformation bands is hosted. Dark gouges and deformation bands display striking distinctive features (i.e., geometric arrangement, grain size distribution, displacement, fractal dimension and clast preferential orientation), suggesting their genesis occurred under different slip rates. Based on grain size distribution data, total surface energies required for dark gouge and deformation band development are in the order of 106 and 104 J/m2, respectively. These values are in accordance with literature fault scaling laws regarding moment magnitude-surface energy relationship. Our results support the genesis of deformation bands during inter-seismic, creeping fault activity periods, while dark gouges were produced during coseismic slip events

Displacement-dependent microstructural and petrophysical properties of deformation bands and gouges in poorly lithified sandstone deformed at shallow burial depth (Crotone Basin, Italy)

We present the results of meso-and micro-structural analyses performed on fault-related soft-sediment deformation structures affecting poorly lithified, high-porosity siliciclastic sediments in the Crotone Basin, Southern Italy. The investigated extensional fault zone has a total displacement of ~90 m and juxtaposes marine clayish sediments in the hanging wall against arkosic to lithic arkosic sandstone in the footwall. In the footwall damage zone, deformation is achieved by a network of conjugate deformation bands, whereas the foliated fault core hosts cm-thick gouges. Deformation bands and black gouges accommodated displacement between 0.2 and 20 cm. Microstructural observations and quantitative image analysis pointed out that particulate flow operated during the early stages of faulting, followed by cataclasis after significant porosity loss. Mineralogy of clasts controlled grain-scale deformation mechanism: following this, feldspar experienced extensive intragranular crushing, while quartz grains were deformed mainly by splitting and abrasion. Permeability of pristine sandstone spans from 5.4 × 104 to 1.4 × 105 mD, while inside deformation bands is reduced by 1-2 orders of magnitude, reaching 3-4 orders of magnitude within fault gouges. Permeability drop inside the fault zone is related to the accommodated displacement along each deformation structure, potentially leading to hydraulic compartmentalization of high-porosity sandstone reservoir

The influence of density on the fracture energy of AAC: From experimental investigation to the calibration of a cohesive law

The paper investigates cracking development in Autoclaved Aerated Concrete (AAC) elements, and clarifies the effect of density and porosity on material mechanical properties. To this purpose, 4 material densities are analyzed, ranging from 300 kg/m3 to 580 kg/m3, corresponding to a compressive strength interval approximately ranging from 1.90 MPa to 5.50 MPa. Fracture mechanics of AAC is analyzed by carrying out three-point bending tests on notched beams, similar to those commonly used for normal concrete elements. In these tests, the onset and development of crack pattern is studied by means of Digital Image Correlation technique. An almost linear dependence of fracture energy from density (and consequently from strength) is derived based on test results. Experimental results are used to calibrate a bi-linear cohesive law, whose parameters vary with material density, so allowing to differentiate fracture properties for structural (high density) and non-structural (low density) AAC elements in finite element analyses. The cohesive law parameters are calibrated by exploiting a neural network algorithm and interfacing MatLab with ABAQUS Finite Element package. The curves obtained for the 4 investigated densities, normalized with respect to material tensile strength, are almost superimposed on each other as if the stresses were scaled with porosity. The displacements corresponding to the knee of the curve are nearly coincident, independently from material density. The good agreement between experimental and numerical results proves the reliability of the proposed approach